Elementary Particles and Fields and String Theory Commons^™

Jets And Underlying Event In √S_Nn = 200 Gev P+Au Collisions At Rhic, Veronica Verkest

Wayne State University Dissertations

Small collision systems, such as that between a proton or deuteron and a heavy-ion, were originally studied to assess cold nuclear matter (CNM) effects but have produced surprising results at RHIC and the LHC over the last several years. Namely, observations of jet yield suppression (enhancement) in central (peripheral) p/d+A events have motivated further investigations into small systems, including the search for signs of Quark-Gluon Plasma (QGP) formation. This thesis focuses primarily on an analysis of correlations of hard and soft particle production in √s_NN = 200 GeV p+Au collisions in STAR. Jets and Underlying Event (UE) are measured at …

Analytic Solutions Of The Dglap Evolution And Theoretical Uncertainties, A. Simonelli

Physics Faculty Publications

The energy dependence for the singlet sector of Parton Distributions Functions (PDFs) is described by an entangled pair of ordinary linear differential equations. Although there are no exact analytic solutions, it is possible to provide approximated results depending on the assumptions and the methodology adopted. These results differ in their sub-leading, neglected terms and ultimately they are associated with different treatments of the theoretical uncertainties. In this work, a novel analytic approach in Mellin space is presented and a new methodology for obtaining closed and exponentiated analytic solutions is devised. Different results for the DGLAP evolution at Next-Leading-Order are compared, …

Inverse Mappers For Qcd Global Analysis, Manal Almaeen

Computer Science Theses & Dissertations

Inverse problems – using measured observations to determine unknown parameters – are well motivated but challenging in many scientific problems. Mapping parameters to observables is a well-posed problem with unique solutions, and therefore can be solved with differential equations or linear algebra solvers. However, the inverse problem requires backward mapping from observable to parameter space, which is often nonunique. Consequently, solving inverse problems is ill-posed and a far more challenging computational problem.

Our motivated application in this dissertation is the inverse problems in nuclear physics that characterize the internal structure of the hadrons. We first present a machine learning framework …

Deeply Learning Deep Inelastic Scattering Kinematics, Markus Diefenthaler, Abdullah Farhat, Andrii Verbytskyi, Yuesheng Xu

Mathematics & Statistics Faculty Publications

We study the use of deep learning techniques to reconstruct the kinematics of the neutral current deep inelastic scattering (DIS) process in electron–proton collisions. In particular, we use simulated data from the ZEUS experiment at the HERA accelerator facility, and train deep neural networks to reconstruct the kinematic variables Q² and x. Our approach is based on the information used in the classical construction methods, the measurements of the scattered lepton, and the hadronic final state in the detector, but is enhanced through correlations and patterns revealed with the simulated data sets. We show that, with the appropriate selection …

Form Factors And Two-Photon Exchange In High-Energy Elastic Electron-Proton Scattering, M. E. Christy, T. Gautam, L. Ou, S.L. Allison, D. Bulumulla, F. Hauenstein, C. Hyde, K. Park, M.N.H. Rashad, J. Zhang, Y. X. Zhao, P. Zhu, Et Al.

Physics Faculty Publications

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q²) up to 15.75  (GeV/c)². Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q² and double the range over which a longitudinal or transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q² and attributed to hard two-photon exchange (TPE) effects, extending to 8 (GeV/c)² the range of Q² for which a discrepancy …

Deeply Virtual Compton Scattering Cross Section At High Bjorken 𝓍B, F. Georges, M.N.H. Rashad, A. Stefanko, J. Zhang, Y. Zhao, P. Zhu, Et Al.

Physics Faculty Publications

We report high-precision measurements of the deeply virtual Compton scattering (DVCS) cross section at high values of the Bjorken variable 𝓍_B. DVCS is sensitive to the generalized parton distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton form factors (CFFs) of the nucleon as a function of 𝓍_B, while systematically including helicity flip amplitudes. …

Ruling Out Color Transparency In Quasielastic ¹²C(E,E'P) Up To Q² Of 14.2 (Gev/C)², D. Bhetuwal, J. Matter, H. Szumila-Vance, F. Hauenstein, C. Yero, J. Zhang, Et Al., Hall C. Collaboration

Physics Faculty Publications

Quasielastic ¹²C(e,e'p) scattering was measured at spacelike 4-momentum transfer squared Q² = 8, 9.4, 11.4, and 14.2 (GeV/c)², the highest ever achieved to date. Nuclear transparency for this reaction was extracted by comparing the measured yield to that expected from a plane-wave impulse approximation calculation without any final state interactions. The measured transparency was consistent with no Q² dependence, up to proton momenta of 8.5 GeV/c, ruling out the quantum chromodynamics effect of color transparency at the measured Q² scales in exclusive (e, e'p) reactions. These results impose strict constraints on models of color …

Observation Of Beam Spin Asymmetries In The Process Ep → E'Π⁺Π⁻ X With Clas 12, T. B. Hayward, C. Dilks, A. Vossen, Dilini Bulumulla, Mohammad Hattawy, Florian Hauenstein, Mariana Khachatryan, Sebastian E. Kuhn, Yelena Prok, B. Yale, N. Zachariou, J. Zhang, Et Al., Clas Collaboration

Physics Faculty Publications

The observation of beam spin asymmetries in two-pion production in semi-inclusive deep inelastic scattering off an unpolarized proton target is reported. The data presented here were taken in the fall of 2018 with the CLAS12 spectrometer using a 10.6 GeV longitudinally spin-polarized electron beam delivered by CEBAF at JLab. The measured asymmetries provide the first opportunity to extract the parton distribution function e(x), which provides information about the interaction between gluons and quarks, in a collinear framework that offers cleaner access than previous measurements. The asymmetries also constitute the first ever signal sensitive to the helicity-dependent two-pion fragmentation function …

Unpolarized Gluon Distribution In The Nucleon From Lattice Quantum Chromodynamics, Tanjib Khan, Raza Sabbir Sufian, Joseph Karpie, Christopher J. Monahan, Colin Egerer, Bálint Joó, Wayne Morris, Kostas Orginos, Anatoly Radyushkin, David G. Richards, Eloy Romero, Savvas Zafeiropoulos, On Behalf Of The Hadstruc Collaboration

Physics Faculty Publications

In this study, we present a determination of the unpolarized gluon Ioffe-time distribution in the nucleon from a first principles lattice quantum chromodynamics calculation. We carry out the lattice calculation on a 32³ × 64 ensemble with a pion mass of 358 MeV and lattice spacing of 0.094 fm. We construct the nucleon interpolating fields using the distillation technique, flow the gauge fields using the gradient flow, and solve the summed generalized eigenvalue problem to determine the gluonic matrix elements. Combining these techniques allows us to provide a statistically well-controlled Ioffe-time distribution and unpolarized gluon parton distribution function. We …

First Measurement Of Near-Threshold J/ᴪ Exclusive Photoproduction Off The Proton, M. Ali, M. Amaryan, E.G. Anassontzis, Q. Zhou, X. Zhou, B. Zihlmann, Gluex Collaboration

Physics Faculty Publications

We report on the measurement of the γp -> J/ψp cross section from E_γ = 11.8 GeV down to the threshold at 8.2 GeV using a tagged photon beam with the GlueX experiment. We find that the total cross section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section dσ/dt has an exponential slope of 1.67 ± 0.39 GeV^-2 at 10.7 GeV average energy. The LHCb pentaquark candidates P⁺_c can be produced in the s channel of this reaction. We see no evidence for them and set model-dependent upper …

Azimuthal Anisotropy In Cu+Au Collisions At √SNn = 200 Gev, L. Adamczyk, J. R. Adams, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, K. Barish, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

The azimuthal anisotropic flow of identified and unidentified charged particles has been systematically studied in Cu+Au collisions at √s_NN = 200 GeV for harmonics n = 1–4 in the pseudorapidity range |η| < 1. The directed flow in Cu+Au collisions is compared with the rapidity-odd and, for the first time, the rapidity-even components of charged particle directed flow in Au+Au collisions at √s_NN = 20 GeV. The slope of the directed flow pseudorapidity dependence in Cu+Au collisions is found to be similar to that in Au+Au collisions, with the intercept shifted toward positive pseudorapidity values, i.e., the Cu-going direction. The mean transverse momentum projected onto the spectator plane ⟨p_x⟩ in Cu+Au collision also exhibits approximately linear dependence on pseudorapidity with the intercept …

Pulse Height Spectra Analysis Of A Neutron Energy Tuning Assembly, Jason R. Stickney

Theses and Dissertations

An energy tuning assembly (ETA) was previously designed and built for the purpose of irradiating samples with a combination of a thermonuclear and a prompt fission neutron spectrum. Initial research was performed to characterize the performance of the ETA at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron using 33 MeV deuteron breakup on tantalum as the neutron source. This research analyzes detector responses collected from three EJ-309 detectors used to characterize the ETA generated neutron field. A signal processing chain was developed to reduce the full waveform data into a pulse height spectrum. The primary goal was to develop a …

Exclusive Studiess Of Short Range Correlations In Nuclei Using Clas12 Proposal To Jefferson Lab Pac 46, A. Ashkenazy, R. Cruz Torres, S. Gilad, O. Hen, G. Laskaris, A. Papadopoulou, M. Patsyuk, A. Schmidt, B. Schmookler, E. P. Segarra, F. Hauenstein, M. Hattawy, C. Hyde, M. Khachatryan, S. Kuhn, L. B. Weinstein, E. O. Cohen, M. Duer, E. Piasetzky, D. Higinbotham, S. Stepanyan, H. Szumila-Vance, S. A. Wood, Christopher Marshall, K. Mahn, J. Morrison, L. Pickering, A. Beck, I. Korover, S. Mey-Tal Beck, A. El Alaoui, H. Hakobian, T. Mineeva, J. Miller, W. Brooks, M. Betancourt, T. Katori, I. Balossino, D. Watts, L. Zana, D. Ireland, D. Sokhan, N. Kalantarians, S. Li

Physics Faculty Publications

Short-ranged correlated (SRC) nucleon-nucleon (NN) pairs account for about 20% of all nucleons in medium to heavy nuclei and about 75% of the nuclear kinetic energy. In addition, there is strong evidence linking these pairs to nucleon structure modification in nuclei (the EMC effect). A Significant amount of our knowledge of SRC pairs comes from hard two nucleon knockout measurements, conducted using electron (i.e. (e e'pp) and (e,e'pn)) and proton probes (i.e. (p, 2pn)). These studies show that almost all high-momentum nucleons belong to SRC pairs, that these pairs are predominantly pn pairs …

Measurement Of Deep Exclusive Π- Production Using A Transversely Polarized ³He Target And Solid Spectrometer, J. Arrington, K. Hafidi, M. Hattawy, P. Reimer, S. Riordan, Z. Ye, Z. Ahmed, G. R. Ambrose, S. Basnet, R. S. Evans, G. M. Huber, W. Li, D. Paudyal, Z. Papandreou, H. Gao, X. Li, T. Liu, C. Peng, W. Xiong, X. F. Yan, Z. Zhao, A. Camsonne, J-P. Chen, S. Covrig-Dusa, D. Gaskell, T. Brecelj, M. Milhovilovič, S. Širca, S. Štajner, K. Aniol, M. Boer, D. Dutta, L. Ye, C. E. Hyde, F. R. Wesselmann, P. Markowitz, V. Sulkosky, E. Voutier

Physics Faculty Publications

We propose to measure the transverse nucleon, single-spin asymmetries AUT (Φ, Φs) in the exclusive n→(e, e'π-)p reaction, during the transversely polarized ³He target SIDIS experiment (i.e. E12-10-006 [1]) with SoLID [2]. In principle, as many as six azimuthal modulations of the form Asin(μΦ+λΦS)/UT contribute (where μ and λ are integers) [3], but four of these modulations are small and the physics interest is concentrated in the largest two.

Our primarily goal is the measurment of A sin (Φ-Φs)/UT. This polarization observable has been noted as being sensitive to the spin-flip generalized parton distribution (GPD) E, and factorization studies have …